circuitpython/tests/extmod/vfs_userfs.py

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# test VFS functionality with a user-defined filesystem
# also tests parts of uio.IOBase implementation
import sys
try:
import uio
uio.IOBase
import uos
uos.mount
except (ImportError, AttributeError):
print("SKIP")
raise SystemExit
class UserFile(uio.IOBase):
def __init__(self, mode, data):
assert isinstance(data, bytes)
self.is_text = mode.find("b") == -1
self.data = data
self.pos = 0
def read(self):
if self.is_text:
return str(self.data, "utf8")
else:
return self.data
def readinto(self, buf):
assert not self.is_text
n = 0
while n < len(buf) and self.pos < len(self.data):
buf[n] = self.data[self.pos]
n += 1
self.pos += 1
return n
def ioctl(self, req, arg):
print("ioctl", req, arg)
return 0
class UserFS:
def __init__(self, files):
self.files = files
def mount(self, readonly, mksfs):
pass
def umount(self):
pass
def stat(self, path):
print("stat", path)
if path in self.files:
return (32768, 0, 0, 0, 0, 0, 0, 0, 0, 0)
raise OSError
def open(self, path, mode):
print("open", path, mode)
return UserFile(mode, self.files[path])
# create and mount a user filesystem
user_files = {
"/data.txt": b"some data in a text file",
"/usermod1.py": b"print('in usermod1')\nimport usermod2",
"/usermod2.py": b"print('in usermod2')",
}
uos.mount(UserFS(user_files), "/userfs")
# open and read a file
f = open("/userfs/data.txt")
print(f.read())
# import files from the user filesystem
sys.path.append("/userfs")
import usermod1
# unmount and undo path addition
uos.umount("/userfs")
sys.path.pop()